Valve-gear for internal-combustion engines



R. P. DOXFORD AND K. 0. KELLER VALVE GEAR FOR INTERNAL COMBUSTIONENGINES.

Patented Mar. 16, 1920.

APPLICATION FILED DECJZO, 191?.

R. PLDOXFORD'AND K. O. KELLER.

VALVE GEAR FOR INTERNAL COMBUSTION ENGINES. AEPLICATION FILED DEC. 20,1917.

Patented Mar.16,1920.

3 SHEETS-SHEET 2.

R. P. DOXFORD AND K. OQKELLER. VALVE GEAR FOR INTERNAL COMBUSTIONENGINES.

APPLICATION FILED DEC. 20, I917. I

' Patented Mar. 16, 1920.

3 SHEEIS-SHEET 3.

Wlbzesses 3 (1 f wv'fiuwm I UNITED STATES PATENT OFFICE.

ROBERT P. DOXFORD AND KARL OTTO KELLER, OF SUNDEBLAND, ENGLAND.

VALVE-GEAR FOB. INTERNAL-COMBUSTION ENGINES.

Specification of Letters Patent.

Patented Mar. 16, 1920.

T 0 all whom it may concern:

Be it known that we, ROBERT PILE Dox- FORD, a subject of the King ofEngland, and KARL OTTO KELLER, a citizen of Switzerland, both residingat Sunderland, in the county of Durham, England, have invented certainnew and useful Improvements in Valve-Gears for Internal-CombustionEngines, of which the following is a specification.

This invention relates to valve-operating gears that are employed forthe fuel-injection valves of internal-combustion engines employingmechanical injection, when the action of the fuel-delivering devicecontrolling the amount of fuel-oil to be sprayed into the cylinder is tobe altered whenever a change in the speed of the engine, or a change inits power, or in both, is desired.

In some such engines it has been proposed to control, by varying thedischarge from the fuel-pump, the amount of fuel-oil injected into thecylinder, the requisite oilprcssure necessary for the mechanicalatomization having been obtained by a springloadcd automatic valve. Insuch cases difficulties arose at light loads owing to the smallness ofthe amount of fuel-oil to be pumped for each explosion stroke of theeuine. g To overcome this difficulty it was proposed to control, bymechanically varying the action of a fuel-injection valve, the amount offuel oil to be injected. This was done by inter-posing between the valveand its opcratingcam, a single lever pivoted on an adjustable eccentricemployed as a pivotpin. The cam actuated one end of the lever and theinjection needlevalve was actuated by the other end of the same lever.The ac tion of the injection needle-valve was varied in this device byshifting the eccentric pin through a small angle, to shift theleverfulcrum and with itthe lever in relation to the cam. Difficultiesarose with this construction in arranging for the desired lifts andtimings of the needle-valve; because al though a cam and single lever,relatively adjustable as described, could be made to ive a lift andtiming suitable for what might be termed a normal operation of the valve(say for full load), yet that cam being necessarily shaped to suit suchnormal operation imposed limitations when attempts were made to obtainthe desired other lifts and timings by relative adjustment'between thesame cam and the single lever.

The present invention concerns an improvement whereby, with the aid of acombination of two levers each receiving, so long as the distribution isnot to be altered, a simple oscillatory motion on its fulcrum, onefulcrum and lever receiving a motion of translation at only such timesas the distribution is to be changed, and a modifying-- cam between thelevers, the lift and timings of the injection needle-valve can be madesuch as to give the best results at all loads, either in an engine withconstant speed or in one with variable speed.

In the accompanying drawings- Figure 1 is a side elevation showing twoinjection-valves of one cylinderlof an engine and devices whereby theyare operated according to the present invention;

Fig. 2 is a view generally similar to Fig. 1 of an alternativeconstruction hereinafter particularly described.

Fig. 3 is a part side elevation of the apparatus according to Fig. 1with the front valve-operating lever broken away, and

Fig. 4 is a corresponding View of the apparatus according to Fig. 2.

Like reference-letters indicate like parts throughout the drawings.

With reference first to Fig. 1, the construction comprises thecombination with the rotatable cam RC and a rocking-lever 1 pivoted onan adjustable fulcrum F and simply rocked by the rotatable cam leverreceiving any translatory motion therefrom, of a second lever 2 placedbetween the rocking lever and the fuel-valve FV together with a cam MGcarried on the second lever. The cam MC may be termed a complementaryormodifying-cam, and it is so shapeo that in all the positions into whichthe rocking-lever is adjustable in relation to the second lever (and aseries of such positions into which the roller R and, correspondingly,the left-hand end of the lever I carry- I mg it, can be shifted by suchadjustment of the rocking-lever, when the distribution is to be altered,is shown by the chain-lined circles R R R B), it causes the motionimparted by the rotatable cam RC through the rocking-lever 1 to the"second lever 2 to be corrected or modified; thus the motions impartedby the second lever 2 to the valve FV are not limited as they would bein a combination of the rotatable cam RC With a solitary rocking-leversuch as 1, and consequently can be those which are appropriate for thevarious lifts and timings desired. At the same time greater freedom canbe exercised in the design of the rotat able cam RC than when a singleadjustable lever was, as hereinbefore described, the only operativeintermediary between the rotary cam and the needle-valve FV A convenientarrangement of the complementaryor modifying-cam MC is one in which itlies, as shown, along the righthand end of the second lever 2 anddetermines the form of the path in which the contiguous (left-hand) endof the rockinglever l is moved alongit in the adjustment of theadjustable fulcrum F, i. c. the path in which. the circles R R R R Rappear, for the spring S keeps the roller against the underface of thecam MC during this adjustment.

This arrangement is particularly adapted for use in reversing engines.The modifying-cam MC shown in Fig. l is virtually a pair of cams, forthe left-hand end of the cam in the drawing is the ahead cam inasmuch asit is so shaped that it will be given maximum movement, effecting amaximum opening of the valve FV for running in one direction, 1?. e.ahead when the roller R is under its left-hand end, the amount of thisopening gradually diminishing to m'l as the roller R is moved from theposition in which it is shown in full lines into the position indicatedby the chainline circle R Theright-hand end of the cam MC in the drawingis the astern cam inasmuch as it is so shaped that it will be givenmaximum movement, effecting a maximum open ing of the valve FV forrunning in the other direction, 2'. e. astern when the roller R is underits right-hand end, the amount of this asternopening graduallydiminishing to m'l as the roller moves from the position shown by thecircle R into the position shown by the circle R".

The rightand left-hand lower faces of the cam MC are joined by a neutralor straight portion as shown, and in that portion of the adjustment ofthe rocking-lever 1 which carries the roller R from the position Bthrough the position R into the position R and vice versa the lever willbe in a neutral position in which it will not be actuated by therotatable cam RC. Thus, by this employment of the modifying-cam invirtual pairs, a continuous adjustment, when the distribution is to bealtered, of the rockinglever l by the shift of its adjustable fulcrum Fcan cause it to pass from operative relationship with the ahead camthrough a neutral position into operative relation ship with the asterncam. lVhen reversal of the engine is to take place and this change ofoperative relationship is to be effected, the fulcrum pin F carried bythe crank F will be shifted in the arc of a circle by rock- 'ing the amF it will be connected with the manually operating gear in the case of amarine engine.

The second lever 2, which operates the injection needle-valve F V hasfor its own fulcrum a pin EP which has a small eccentricity in relationto the bearing B in which it is held, and it is used for the purpose ofaccurately making (in a manner well understood) what may be termed afine adjustment of the lift imparted to the needlevalve FV by the secondlever; this fine adjustment may be made while the engine is running.This pin is stationary except when it is being used to make on occasionthis fine adjustment.

In Fig. 1 there is a second fuel-valve FV worked by a lever 2 similar tothe lever 2 and having, like the latter, a modifyingcam upon it. Thisvalve F V opens into the same cylinder as the valve Fl, an arrangementwhich is particularly convenient in an engine, such as a marine engine,required to run at a variable speed. In such an engine the power to bedeveloped varies very greatly, and it is convenient to bring the fuelvalves successively into, as well as out of, operation according to theincrease and decrease, respectively, of speed and power. Themodifying-cam for the lever 2 is concealed behind the cam MC of thelever 2 in Fig. 1, but is clearly shown in Fig. 3 in which the lever 2is broken away. It is shaped like the cam MC except that its lower faceis recessed, as shown at line HS. in order that the action of the lever2 and of the corresponding fuel-valve FV may be out out in the movementof the roller R, consequent upon the adjustment of the fulcrum F in achange of distribution, at times different from those at which theaction of the lever 2 is cut out. For example, in the movement of theroller R into the position R it will be clear of the recessedmodifying-cam on the lever 52 before it is clear of the cam MC on thelever 2; similarly, in moving from the position through the position Rand onward to the right, it will be operative upon the cam MC as soon asit arrives in the position R but it will not be operative upon themodifyingcani of the lever 2 until it has moved beyond the position Rpast the recess, toward the position R Thus, the cutting out of actionof one fuel-injection valve FV is not effected until after the valve FVhas been cut out, in moving from ahead to-' ward astern, and incontinuing that movement past the neutral position the fuelvalve FV willbe cut in again before the valve FV is cut in. And of course the twoends of the virtual duplex cams MC need not be identical in shape, forit may not be necessary to have so much fuel coming into the cylinder inastern running as is wanted for ahead running.

In the example illustrated in the drawing, both the levers 2 and 2 areoperated by the same roller R carried on a single rockinglever; but eachvalve could be given its own rocking-lever 1.if desired.

In the construction illustrated in Fig. 2, the second levers 2 and 2operate separate fuel-injection valves by means of the rods VH and VRrespectively. The two second levers are both operated by a rocking-lever1 and rotatable cam RC as in the former case, but the modifying-cam MCis singleended as the arrangement is intended for ahead running only,and in the successive positions R R into which the roller R passes inmoving to the right from the position in which it is shown in thedrawing, in a change of distribution, it will pass less and less lift tothe fuel-valve until it arrives in such positions as R and R in whichthe fuel-valves will be out of action altogether. The modifying-cam onthe second lever 2 in this figure is concealed behind the modifying-camMC of the lever 2 but is clearly shown in Fig. 4 in which the lever 2 isbroken away, and is slightly different in shape as is shown by thedotted line at I) (Fig. 2) so that the roller R in moving from theposition in which it is shown in full lines toward the right with thelever 1 will begin to lessen the opening of the valve that is effectedby the second lever 2 before it lessens the opening of the companionvalve controlled by the lever 2.

It is to be understood that the adjustable pivots or fulcra F of theseveral rockinglevers such as 1 in Figs. 1 and 2 can all be actuatedsimultaneously by automatic or manual means when the distribution is tobe changed; they may be constituted by small cranks, as shown at F on ashaft. lie the case of a stationary engine these cranks can be under theinfluence of the governor. The proportions of the respectiverocking-levers 1 and intermediate levers 2 and the amounts of movementgiven to the respective pivots of the former may be arranged as desired,for the proportions of the levers l and 2 the cams MC and the adjustments allotted to different valves need not be identical.

The complementaryor modifying-cams are applicable in the manner abovedescribed to engines running at constant speeds as Well as to engines inwhich the speeds are variable; but of course the lifts and timings forthe valves in the former case and therefore the shapes of the cams,would be different from those which would be employed in the lattercase.

hat we claim as our invention and desire to secure by Letters Patentis 1. In an internal combustion engine, the combination with afuel-injection valve and a main cam for controlling the same, of anadjustable fulcrum piece, an operating lever mounted to rock about saidfulcrum .piece and having one end which receives from the cam a motionwhich is only a simple rocking motion, and a valve lever mounted to rockabout another fulcrum piece and operatively connected with said valve,one of said levers having a cam face coacting directly with and bearingimmediately on the other lever and adapted to impart the rockingmovement of the operating lever in modified form to the valve lever,substantially as described.

2. In an internal combustion engine, the combination with afuel-injection valve and a main cam for controlling the same, of anadjustable fulcrum piece, an operating lever mounted to rock about saidfulcrum piece and having one end which receives from the cam a motionwhich is only a simple rocking motion, and a valve lever mounted to rockabout another fulcrum piece and operatively connected with said valve,one of said levers having a cam face co-acting directly with and bearingimmediately on the other lever and adapted to impart the rockingmovement of the operating lever in modified form to the valve lever, thesaid cam-face comprising an ahead portion at one end, and an asternportion at the other end, and an intermediate neutral portion betweenthe two ends which are disposed one behind the other in the path inwhich the adjustable fulcrum piece adjusts the said operating lever,substantially as described.

3. In an internal combustion engine the combination with a plurality offuel-injection valves and a main cam for controlling the same, of anadjustable fulcrum piece, an operating lever mounted to rock about thesaid fulcrum piece and normally adapted to be actuated by said main cam,and a plurality of valve levers. one of said valve levers beingopcratively connected to each valve and each of said valve levers beingmounted to rock about a fulcrum piece difplurality of cams beingsituated between the ferent from that of the operating lever, and namesto this specification in the presence 10 a plurality of differentlyshaped cams, one of two subscribing Witnesses.

of said cams being appropriated to the opr eration of each of the valvelevers, the said i E 7 ends of the valve levers and the eoacting\Vitnesses to the signature of Karl Otto part of the said operatinglever, substan- Keller: tially as described. H. NIXON,

In testimony whereof We have signed our A. MrroHnNsEN.

